For better or worse, the fly fishing world revolves around trout. Don't get me wrong... I love trout. I respect their fickle nature. I think they're graceful animals...deceptively powerful in strong currents...and noble adversaries vis a vis the tug. And they're more predatory than most of us give them credit for being (at least the big ones are). If you don't believe that, go throw a mouse fly in a trout river at night, and see if that won't change your mind.